Rose in her "The Encyclopedia of Quantrill's Guerrillas" lists a number of good references for William Francis Hadley and his farewell performance for the Union tribunal at Warrensburg in May 1864. I suppose from Hadley's perspective the Yanks had him dead to rights with no way out from an execution, so he "laid it on thick."
It seems Hadley was not exaggerating in all that he said. The problem for us is that Hadley is from Platte County, and not as well known to us as Quantrill's Jackson County men, so he almost comes to us "out of the blue."
I found in the 1860 Missouri Census the John Davis household in Lee Township, west-central Platte County near Farley that contained 21-year-old, Indiana-born laborer Wm. Hadley. I know the "Liberty Tribune" newspaper article of 17 June 1864 said Hadley was born in New Hampshire in May 1842. Well, the census-takers sometimes made mistakes as did the newspaper reporters, so who do we believe? The period newspapers mentioned that Hadley worked prewar driving stagecoaches, so maybe the census-taker didn't find Hadley home when he was making his rounds and had to rely on a neighbor to tell him about the young man and where he was born.
The Liberty newspaper also said Hadley joined Silas Gordon's company on 16 January 1862, and, indeed, Rose directs us to Paxton's 1897 "Annals of Platte County," on page 323 that tells us that Silas Gordon's guerrilla company from Platte County was sworn into Confederate service at Springfield with Will Hadley as a member. Since much of Si Gordon's unit was composed of Platte County men, the census report about the Indiana laborer in the census of Platte County does fit. Also, the Missouri State Archives has a brief military service record for "W. F. Hadley" as a member of Company I, 1st Missouri Cavalry Regiment (CSA). James McGhee's new book, "Guide to Missouri Confederate Units, 1861-1865" on page 48 does state that Company I of this regiment was from Platte County and was commanded by Captain Silas M. Gordon. At least that part of Hadley's confession seems to be true.
Other newspaper coverage of Hadley's long confession and execution by musketry on 20 May 1864 can be found in the 1 July 1864 edition of the "Missouri Statesman" of Columbia taken from the "Missouri State Times" of Jefferson City. Also you can find this in the 25 May 1864 edition of the St. Louis "Daily Missouri Democrat" and the Kansas City "Western Journal of Commerce" of 18 June 1864.
There are valuable clues in Hadley's detailed confession. He mentioned that he joined Quantrill with his band of 28 men in Jackson County in August 1862, but was wounded in the shoulder and had his horse killed during the 6 October 1862 fight at Sibley. The shoulder wound may have put him out of action for a while. If I recall my reading correctly, Captain Fernando Scott brought his band of Platte, Clay, and Ray County guerrillas over south of the Missouri River to Quantrill about the time Hadley said he joined Quantrill. Either Hadley stretched the truth about who led those 28 men or he really did have his own guerrilla band in summer of 1862. To support Hadley's claim that he led his own guerrilla band, he recited several specific skirmishes north and south of the Missouri River from 1861 through 1862 where he named specific members of his gang by name and the approximate dates they were killed. I checked a couple of those names he dropped against the 1860 MO Census and those men did live in the region where he said those things happened.
The St. Louis newspaper article seemed to say that Union district commander Brigadier General Egbert Brown (who had moved his headquartes to Warrensburg that spring) ordered Hadley to be executed after he heard Hadley assert that he rode with Quantrill on the Lawrence Raid on 21 August 1863. Area Union commanders and even Brown himself ordered other men executed who had admitted they "rode with Quantrill on the Lawrence raid," so a predecence had been set.
Even though we haven't heard much about this guy, I tend to believe most of the details he left to us from his windy confession. I think he raised his spirits as he was about to face death by recalling all of his accomplishments for the southern cause. It may have fed his battered ego that somebody was actually writing down all that he said, too. Maybe that made the man feel he wasn't going to die for some obscure act but a whole string of fights against the Federals. That must have been important to him.